1. Technical Field
The present invention relates to a method for fabricating calcium carbonate nanoparticles dispersed in water from ground calcium carbonate particles having a size of several micrometers through a milling.
2. Description of the Related Art
In general, nanoparticles refer to particles with a particle size of 100 nanometers (nm) or smaller. Because of a high surface area to volume ratio and new functionality, they are widely utilized as a new material.
Calcium carbonates are available in forms: ground calcium carbonate (GCC) or precipitated calcium carbonate (PCC). Ground or precipitated calcium carbonate particles are widely used as a filler in the manufacture of paper, plastics, rubber, paints, and the like.
Ground calcium carbonate is prepared by mechanically grinding ultrafine crystalline calcite and classifying the same. In general, it has a mesh size of 325 or smaller.
Various methods are applied to attain smaller-sized calcium carbonate particles, including multi-step dry grinding followed by classification, or a combination of wet grinding, spray drying and dry grinding followed by classification, as disclosed in Korean Patent No. 2003-95142 or 128061. However, in spite of the improvement of grinding and classification techniques, an average particle size of about 1 μm is the best result for ground calcium carbonate obtained in dry powder form.
In contrast, precipitated calcium carbonate refers to calcium carbonate prepared from chemical processing of calcite having a particle size ranging from 10 nm to 10 μm. Precipitated calcium carbonate is in general more expensive than ground calcium carbonate because it is prepared following the processing into quicklime and slaked lime, and carbonation, and it has a smaller particle size.
Not only the grinding of calcium carbonate, but also the dispersion of the ground particles is important. If the ground particles aggregate, they may not exhibit wanted characteristics as a filler.
Techniques of dispersing calcium carbonate in water are disclosed in Korean Patent Nos. 2004-105291 and 2008-36117, Japanese Patent No. 2007-254524, and so forth. However, these are no more than dispersing once-prepared calcium carbonate using a surfactant.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.